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42 Cards in this Set
- Front
- Back
The term gene expression refers to the:
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process by which genetic information flows from genes to proteins
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The cells that make up the various tissues of an animal are so different because:
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only certain genes in each cell type are expressed
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The lac operon is found:
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in E. coli
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The lac operon:
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both A and B are correct
A. prevents lactose-utilizing enzymes from being expressed when lactose is absent from the environment B. coordinates the production of lactose-utilizing enzymes when lactose is present in the environment |
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RNA polymerase binds to which of the following?
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the promoter
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In the lac operon, a regulatory gene outside of the operon is always producing ___, which (in the absence of lactose) binds to the ___.
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a repressor, operator
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The lac operon is ___ when the repressor is bound to lactose.
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active
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Specialization in the structure and function of cells that occurs during the development of a multicellular organism is called:
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cellular differentiation
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The basis of cellular differentiation is:
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selective gene expression
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The production of an organism that is genetically identical to another organism is called:
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cloning
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The result of cloning is an offspring who is always genetically identical to the organism that supplied:
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the nucleus
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Cells from a differentiated part of a plant can be removed, placed into nutrient medium, and the cells may grow into a complete plant. This shows that:
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differentiation does not involve irreversible changes in DNA
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Which of the following types of cells has the greatest potential for differentiation?
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embryonic stem cells
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If the DNA in a human cell was stretched out straight, how long would it be?
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3 meters long
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In the eukaryotic nucleus, the unit that consists of DNA wound around a core of eight histone proteins is called a:
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nucleosome
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Dense packing of DNA in chromosomes:
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prevents gene expression
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X-chromosome inactivation
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can lead to a tortoiseshell pattern in cats
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In eukaryotic cells, enhancers and activators regulate:
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transcription
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In eukaryotic cells, transcription factors can bind to:
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all of the above
A. enhancers B. the promoter C. RNA polymerase |
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Regions of noncoding DNA within a gene are called:
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introns
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The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called:
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exons
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RNA splicing involves the:
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removal of introns from the molecule
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Which of the following is an explanation of why a single gene may code for more than one polypeptide?
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alternative RNA splicing
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After a polypeptide is produced, it may need further processing before it becomes an active protein. This activation of the protein in a eukaryotic cell:
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occurs in the cytoplasm
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Which of the following is a eukaryotic mechanism that regulates the amount of the active protein in a cell?
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all of the above
A. breakdown of mRNA B. regulation of translation initiation C. activation of the protein D. breakdown of the protein |
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In egg development or early embryonic development of animals, proteins are carried back and forth between cells to help guide development. This is called:
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cell-to-cell signaling
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A master control gene that regulates many other genes, and determines the identity of a body structure of a developing organism is called:
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a homeotic gene
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A signal molecule from one cell will bind to:
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a receptor protein in the membrane of the target cell
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A signal molecule from one cell can activate transcription factors in a target cell by:
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triggering a signal-transduction pathway
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Developmental similarities observed in most vertebrates are probably due to:
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nucleotide sequences called homeoboxes that have changed very little over time
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Homeoboxes of very similar sequences are found in:
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virtually all eukaryotic organisms
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Homeoboxes function as control mechanisms by:
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switching homeotic genes on and off
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Why can organisms be so different, yet still have very similar homeoboxes?
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Homeoboxes simply function as switches to turn homeotic genes on and off. Homeotic genes can still vary considerable among different organisms.
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A gene that causes cancer is called a:
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oncogene
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A normal gene with the potential to become an oncogene is called a:
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proto-oncogene
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The normal role of most proto-oncogenes is to:
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regulate the cell cycle
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The role of a tumor-suppressor gene it to:
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inhibit cell division and uncontrolled cell growth
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A mutant tumor-suppressor gene:
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produces a defective protein unable to function in a pathway that normally inhibits cell division
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Many cancers, such as colon cancer, can take a long time to develop because:
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it does not arise until several mutations have accumulated
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Why is cancer always a "genetic disease?"
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it is always the consequence of changes in DNA
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Why are most breast cancer cases considered to be "nonhereditary?"
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most breast cancers are due to somatic cell mutations, not inherited mutations
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The carcinogen known to cause the most cases of cancer is:
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tobacco
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